Reaction products of aminoalkylenecarboxylic acids and mineral oil middle distillates which contain them

ABSTRACT

Reaction products of amino-alkylenecarboxylic acids with polyoxyalkylene compounds are used as paraffin dispersants for mineral oil middle distillates.

This application is a 371 of PCT/EP94/02122 filed Jun. 29 1994.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reaction products ofaminoalkylenecarboxylic acids, which products are suitable as paraffindispersants, and their use and mineral oil middle distillatecompositions which are based on a hydrocarbon mixture and contain thesereaction products.

2. Discussion of the Background

Middle distillates, for example gas oils, diesel oils or fuel oils,which are obtained by distillation of mineral oils, have differentparaffin contents, depending on the origin of the crude oil. Atrelatively low temperatures, solid paraffins separate out (cloud point,CP). On further cooling, the lamellar n-paraffin crystals form ahouse-of-cards structure and the middle distillate sets although thepredominant part of the middle distillate is still liquid. The flow ofthe mineral oil middle distillates is considerably adversely affected bythe precipitated n-paraffins between the cloud point and the pour point.The paraffins block filters and cause irregular fuel feed to thecombustion units or completely stop this feed.

It has long been known that the crystal growth of the paraffins in themineral oil middle distillates can be modified by suitable additives.Effective additives on the one hand prevent middle distillates fromforming such house-of-cards structures and becoming solid attemperatures a few degrees Centigrade below the temperature at which thefirst paraffin crystals crystallize out and, on the other hand, resultin the formation of fine, well crystallized, separate paraffin crystalswhich pass through filters in motor vehicles and heating systems or atleast form filter cakes which are permeable to the liquid part of themiddle distillates, thus ensuring trouble-free operation.

A disadvantage of this prior art is based on the fact that theprecipitated paraffin crystals have a higher density than the liquidpart and therefore tend to settle out on the bottom of the container toan increasing extent during storage. This results in the formation of ahomogeneous phase having a low paraffin content in the upper part of thecontainer and a two-phase paraffin-rich layer at the bottom. Since themiddle distillate is generally taken off slightly above the bottom ofthe container both in vehicle tanks and in the storage and deliverytanks of mineral oil dealers, there is a danger that the highconcentration of solid paraffins will lead to blockage of filters andmetering means. This danger is all the greater the further the storagetemperature is below the precipitation temperature of the paraffins(cloud point), since the amount of paraffin precipitated is a functionof the temperature and increases with decreasing temperature.

The paraffin crystal modifiers, ie. is flow improvers, are polymerswhich change the crystal growth of the n-paraffins by cocrystallization(interaction). The flow properties of the middle distillate atrelatively low temperatures are advantageously affected. The efficiencyof the flow improvers is expressed indirectly by measurement of the coldfilter plugging point (CFPP), according to DIN 51,428.

Conventional ethylene copolymers, especially copolymers of ethylene andunsaturated esters, are used as low-temperature flow improvers. DE 11 47799 and DE 19 14 756 describe, for example, copolymers of ethylene withvinyl acetate, containing from 25 to 45% by weight of vinyl acetate orvinyl propionate and having a molecular weight of from 500 to 5,000.

Furthermore, GB 2 095 698 discloses that a combination of the statedcopolymers with amides of long-chain amines and aromatic orcycloaliphatic carboxylic acids can be added to middle distillates.

However, these mixtures are still unsatisfactory with regard to thedispersing properties of the precipitated paraffins. It is thereforenecessary for the additives introduced also to effect dispersing of theprecipitated paraffins.

EP-A 398 101 discloses reaction products of aminoalkylenepolycarboxylicacids with long-chain secondary amines, which have been completelyreacted with the amines to give the amide or ammonium salt, as paraffindispersants.

The non-prior-published German Application P 4237662.9 relates toreaction products of amino-alkylenepolycarboxylic acids of long-chainsecondary amines, in which free carboxyl groups or alkali metal oralkaline earth metal carboxylate groups are still present.

These paraffin dispersants are commercially available in general in theform of a concentrated solution in oil-soluble solvents, such ashigh-boiling petroleum ethers or mixtures of aromatics. However, inconcentrated solution, these dispersants may have such a high pour pointthat they are more difficult to handle during transfer or metering.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide paraffin dispersantsfor mineral oil middle distillates, which dispersants have a gooddispersing action as well as a low pour point in concentrated solution.

We have found that this object is achieved by the compounds of theformulae I and II ##STR1## where

A is straight-chain or branched alkylene of 2 to 6 carbon atoms or aradical of the formula III ##STR2## X is ##STR3## and/or a radical ofthe formula IV ##STR4## where R¹ is hydrogen or a straight-chainaliphatic C₁₀ -C₃₀ radical,

R² is a straight-chain aliphatic C₁₀ -C₃₀ radical,

R³ and R⁴ are each hydrogen, methyl or ethyl,

m and n are each from 1 to 5,

x is from 0 to 3,

y is from 1 to 100 and

B is hydroxyl or C₁ -C₃₀ -alkoxy or is naphthyloxy or phenoxy which isunsubstituted or monosubstituted to tri-substituted by C₁ -C₁₈ -alkyl,or is C₁ -C₃₀ -alkylcarboxy or C.sub. -C₃₀ -alkenylcarboxy, or is aminowhich is monosubstituted by a straight-chain aliphatic C₁ -C₃₀ radical,or is amino which is disubstituted by straight-chain aliphatic C₁ -C₃₀radicals, or is C₁ -C₃₀ -alkylamido or alkenylamido or a group of theformula V ##STR5## where the variables have the abovementioned meanings,with the proviso that X is

a) at least one ##STR6## group and

b) at least one group of the formula IV, both conditions beingfulfilled.

We have also found the use of the compounds I and II as paraffindispersants, and mineral oil middle distillates which contain thesecompounds.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The reaction of ethylenetriaminetetraacetic acid,diethylenetriaminetetraacetic acid or nitrilotriacetic acid with aminesHNR¹ R² leads to compounds of the formula I or II, where X is --NR¹ R²or the corresponding ammonium salt --O.sup.⊖ H₂ N.sup.⊕ R¹ R². R¹ and R²are each a straight-chain aliphatic C₁₀ -C₃₀ radical, preferably a C₁₄-C₂₂ radical and R¹ may furthermore be hydrogen. R¹ and R² are eachparticularly preferably a straight-chain aliphatic C₁₀ -C₃₀ radical, inparticular a C₁₄ -C₂₂ radical, ie. amines used for the preparation ofthe compounds I and II are secondary amines. Specific examples ofsecondary amines are dioleylamine, di-tallow fatty amine,dipalmitylamine, di-coconut fatty amine and dibehenylamine andpreferably distearylamine or hydrogenated di-tallow fatty amine (thelatter being of 16 to 18 carbon atoms).

The groups of the formula IV are incorporated in the paraffindispersants I and II by reaction of the compounds VI with the statedpolycarboxylic acids. ##STR7##

The compounds VI are polyoxyalkylene derivatives. R³ and R⁴ are eachhydrogen, methyl or ethyl. m and n are each from 1 to 5. The compoundsare thus obtainable by polymerization of alkylene oxides, such asethylene oxide, propylene oxide or butylene oxide, or by ring cleavageof tetrahydrofuran with polymerization. x and y indicate the degree ofpolymerization. x is from 0 to 5, preferably 0, and y is from 1 to 100,preferably from 1 to 20. If B is hydroxyl, the compounds VI arepolyalkylene glycols, such as polyethylene glycol or polypropyleneglycol, polytetrahydrofuran compounds or mixed copolymers of, forexample, ethylene oxide and propylene oxide. In general, the averagemolecular weight of the glycols is from 200 to 4,000.

Alkoxylated alcohols are also suitable compounds VI. In this case, B isstraight-chain or branched C₁ -C₃₀ -alkoxy, preferably a C₈ -C₂₂radical. They are derived from the corresponding alcohols, such asisotridecanol, isodecanol, decanol, tallow fatty alcohol and stearylalcohol.

The compounds VI furthermore comprise alkoxylated phenols and naphthols,which are unsubstituted or mono-substituted to trisubstituted by C₁ -C₁₈-alkyl. In this class of compounds, B is derived, for example, fromp-cresol, di-tert-butylphenol, isooctylphenol, isononylphenol orβ-naphthol.

Compound VI is an alkoxylated carboxylic acid if B is C₁ -C₃₀-alkylcarboxy or C₁ -C₃₀ -alkenylcarboxy. The carboxylic acids arepreferably straight-chain acids of 8 to 22 carbon atoms, such as stearicacid, lauric acid, oleic acid, behenic acid, tallow fatty acid,2-ethyl-hexanoic acid or isononanoic acid.

B may furthermore be amino which is mono-substituted or disubstituted byaliphatic C₁ -C₃₀ radicals, preferably C₁₀ -C₂₂ radicals. These aminoradicals are derived from amines such as behenylamine, distearylamine,di-tallow fatty amine or hydrogenated di-tallow fatty amine.

Finally, B may be C₁ -C₃₀ -alkylamido or C₁ -C₃₀ -alkenylamido, such asthe radicals of stearylamide and oleamide.

If, in the compounds VI, x is greater than zero, all statedpolyoxyalkylene compounds are present in aminated form. This aminationcan be carried out in a known manner by aminating hydrogenation oraminopropylation of the corresponding hydroxy compounds. If polyglycolsare aminated at both chain ends, compounds VI in which B is of theformula V are obtained.

Compounds I which carry three radicals --NR¹ R² and one radical of theformula IV are preferred.

For the preparation of the compounds I and II, the polycarboxylic acids,at least 1 equivalent of the amines HNR¹ R² and at least 1 equivalent ofthe compounds VI may be mixed and heated to 100°-200° C., and the waterof reaction can be distilled off continuously. The reaction ispreferably carried out in the presence of a catalytic amount of an acidsuch as toluenesulfonic acid.

The novel compounds can be used as paraffin dispersants. They may beadded to mineral oil middle distillates, preferably those having aninitial boiling point above 160° C. and a final boiling point below 420°C.

The compounds of the formulae I and II are added to mineral oil middledistillate compositions as a rule in amounts of from 25 to 1,000 ppm,preferably from 50 to 500 ppm.

The middle distillates usually already contain conventional flowimprovers which are described in detail in the patent literature, forexample in DE 19 14 756 and EP-A 486 836 (ethylene/vinyl estercopolymers and mixtures thereof with other copolymers), EP 214 876(α-olefin/maleic anhydride ester) or EP 155 807 (alkyl fumarate/vinylacetate copolymers).

However, terpolymers which contain further comonomers in addition toethylene and vinyl esters or acrylates are also suitable. The molecularweight of these flow improvers is as a rule from 500 to 5,000,preferably from 1,000 to 3,000. Mixtures of different flow improvers arealso suitable.

The middle distillates can, if required, also contain a conductivityimprover, as described, for example, in DE-A 21 16 556. In addition togood dispersing properties, the compounds I and II have the advantage ofpossessing a low pour point in high concentration in oil-solublesolvents.

EXAMPLES A) Preparation of the Aminoalkylenepolycarboxamides and-Esteramides (Compound I) General Preparation Method for the ParaffinDipsersants PD1-PD8

151.5 g (0.3 mol) of distearylamine, 0.1 mol of compound VI and about1.1 g of p-toluenesulfonic acid were initially taken and melted. At100°-110° C., 29.5 g (0.1 mol) of ethylenediaminetetraacetic acid wereadded. The reaction mixture was heated to 190° C. under a nitrogenatmosphere and condensed at this temperature until the acid number hadfallen below 10 mg KOH/g. The water of reaction distilled off completelyduring this procedure. After filtration, a brown waxy solid wasobtained.

All compounds exhibited the typical amide band at 1650 cm⁻¹ in the IRspectrum. The amidoester additionally exhibited an ester band at 1730cm⁻¹.

PD1: Reaction product of ethylenediaminetetraacetic acid, distearylamineand ethoxylated isononylphenol (molecular weight: 490 g/mol, degree ofethoxylation: 6) in a molar ratio of 1:3:1.

PD2: Reaction product of ethylenediaminetetraacetic acid, distearylamineand ethoxylated isononylphenol (molecular weight: 578 g/mol, degree ofethoxylation: 8) in a molar ratio of 1:3:1.

PD3: Reaction product of ethylenediaminetetraacetic acid, distearylamineand polyethylene glycol (molecular weight: 200 g/mol) in a molar ratioof 1:3:1.

PD4: Reaction product of ethylenediaminetetraacetic acid, distearylamineand polyethylene glycol (molecular weight: 300 g/mol) in a molar ratioof 1:3:1.

PD5: Reaction product of ethylenediaminetetraacetic acid, distearylamineand N-(2-hydroxy-l-methylethyl)-distearylamine in a molar ratio of of1:3:1.

PD6: Reaction product of ethylenediaminetetraacetic acid, distearylamineand polypropylene glycol ether diamine (molecular weight: 2,000 g/mol)in a molar ratio of 1:3:1.

PD7: Reaction product of ethylenediaminetetraacetic acid, distearylamineand N-(hydroxyethyl)-distearylamine in a molar ratio of 1:3:1.

PD8: Reaction product of ethylenediaminetetraacetic acid, distearylamineand propoxylated distearylamine (degree of propoxylation:5 ) in a molarratio of 1:3:1.

B) Testing of the Mineral Oil Middle Distillate Compositions

The following mineral oil middle distillate compositions were tested:

1) as paraffin dispersant PD:

PD1-PD8 ethylenediaminetetraacetic acid derivatives; as comparison PD9(ethylenediaminetetraacetamide A1 from EP-A 398 101)

2) as flow improver F1:

F1 (A) ethylene/vinyl propionate (containing about 40% by weight ofvinyl propionate) having an average molecular weight of about 2,500 (F1(A) from EP-A 398 101)

3) as conductivity improver CV: CV (E) from EP-A 398 101.

The middle distillates used for the following dispersing tests werediesel fuels of commercial German refinery quality; they are referred toas DK 1, DK 2 and DK 3:

    ______________________________________                                                     DK 1     DK 2    DK 2                                            ______________________________________                                        Cloud point CP (°C.)                                                                  -8         -8      -7                                          CFPP (°C.)                                                                            -13        -12     -10                                         Density at 20° C. (g/ml)                                                              0.827      0.831   0.829                                       Initial boiling point (°C.)                                                           165        175     183                                         20% boiling point (°C.)                                                               210        223     211                                         90% boiling point (°C.)                                                               318        314     317                                         Final boiling point (°C.)                                                             358        352     364                                         ______________________________________                                    

Description of the Test Method:

Different amounts of paraffin dispersants PD 1-PD 8 or PD 9 (in eachcase as a 50% strength solution in Solvesso® 150 (high-boiling mixtureof aromatics having a boiling range of from 186° to 206° C., from Esso),flow improver F1 and conductivity improver CV were added to the middledistillates at 40° C. while stirring, and the mixture was then cooled toroom temperature.

The middle distillates containing additives were stored in 100 mlmeasuring cylinders for from 16 to 20 hours in a freezer at -13° C. orat -18° C. The volume of the paraffin phase which had settled out (% byvolume) and the appearance of the oil phase were then assessed visually.

The results are shown in Tables I-III. It can be seen that, in themiddle distillates, compounds PD 1-PD 8 have a dispersant effect whichis just as good as that of comparative compound PD 9.

The advantage of the novel compounds is that their 50% strength solutionin a solvent has a lower pour point than the solution of PD 9 (cf.Table. IV), which substantially facilitates handling in practice.

                                      TABLE I                                     __________________________________________________________________________    Dispersing test in DK 1, CP: -8° C., CFPP: -13° C.                    Dose                                                                              FI  CV  Temp.                                                                             Time                                                                             Paraffin sediment                                                                     Appearance of                                PD#   (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (°C.)                                                                      (h)                                                                              (% by volume)                                                                         oil phase                                    __________________________________________________________________________    1     100 200 3   -13 16 5       dispersed                                    1     100 300 3   -18 20 0       dispersed                                    2     100 300 3   -18 20 0       dispersed                                    3     200 200 3   -18 20 3       dispersed                                    4     200 200 3   -18 20 5       dispersed                                    Comparison:                                                                   9     100 300 3   -18 20 0       dispersed                                    __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    Dispersing tests in DK 2, CP: -8,C, CFPP: -12° C.                            Dose                                                                              FI 1                                                                              CV (E)                                                                            Temp.                                                                             Time                                                                             Paraffin sediment                                                                     Appearance of                                PD#   (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (°C.)                                                                      (h)                                                                              (% by volume)                                                                         oil phase                                    __________________________________________________________________________    1     100 200 3   -13 16 5       dispersed                                    1     100 300 3   -18 20 0       dispersed                                    2     100 300 3   -18 20 0       dispersed                                    5     100 200 3   -13 16 0       dispersed                                    7     100 200 3   -13 16 0       dispersed                                    Comparison:                                                                   9     100 300 3   -18 20 0       dispersed                                    __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________    Dispersing tests in DK 3, CP: -7° C., CFPP: -10° C.                   Dose                                                                              FI 1                                                                              CV (E)                                                                            Temp.                                                                             Time                                                                             Paraffin sediment                                                                     Appearance of                                PD#   (ppm)                                                                             (ppm)                                                                             (ppm)                                                                             (°C.)                                                                      (h)                                                                              (% by volume)                                                                         oil phase                                    __________________________________________________________________________    1     100 200 3   -13 16 5       dispersed                                    1     100 300 3   -18 20 0       dispersed                                    2     100 300 3   -18 20 0       dispersed                                    5     100 200 3   -13 16 0       dispersed                                    6     100 200 3   -13 16 0       dispersed                                    7     100 200 3   -13 16 0       dispersed                                    8     100 200 3   -13 16 0       dispersed                                    Comparison:                                                                   9     100 300 3   -18 20 0       dispersed                                    __________________________________________________________________________

                  TABLE IV                                                        ______________________________________                                        Pour points of compounds PD 1-PD 7                                            as 50% strength solutions in Solvesso 150                                     PD #            Pour point (°C.)                                       ______________________________________                                        PD 1            +5                                                            PD 2            +3                                                            PD 3            +11                                                           PD 4            +13                                                           PD 5            +15                                                           PD 6            +3                                                            PD 7            +13                                                           PD 8            +2                                                            PD 9 (Comparison)                                                                             +19                                                           ______________________________________                                    

We claim:
 1. An aminoalkylenecarboxylic acids of the general formula Ior II ##STR8## where A is straight-chain or branched alkylene of 2 to 6carbon atoms or a radical of the formula III ##STR9## X is ##STR10## ora radical of the formula IV ##STR11## where R¹ is hydrogen or astraight-chain aliphatic C₁₀ -C₃₀ radical,R² is a straight-chainaliphatic C₁₀ -C₃₀ radical, R³ and R⁴ are each hydrogen, methyl orethyl, m and n are each from 1 to 5, x is from 0 to 3, y is from 1 to100 and B is hydroxyl or C₁ -C₃₀ -alkoxy or is naphthyloxy or phenoxywhich is unsubstituted or monosubstituted to tri-substituted by C₁ -C₁₈-alkyl, or is C₁ -C₃₀ -alkylcarboxy or C₁ -C₃₀ -alkenylcarboxy, or isamino which is monosubstituted by a straight-chain aliphatic C₁ -C₃₀radical, or is amino which is disubstituted by straight-chain aliphaticC₁ -C₃₀ radicals, or is C₁ -C₃₀ -alkylamido or alkenylamido or a groupof the formula V ##STR12## where the variables have the abovementionedmeanings, with the proviso that X is a) at least one ##STR13## group andb) at least one group of the formula IV, both conditions beingfulfilled.
 2. A compound as claimed in claim 1, in which R¹ is hydrogenor a straight-chain aliphatic radical of 14 to 22 carbon atoms and R² isa straight chain aliphatic radical of 14 to 22 carbon atoms.
 3. Acompound of the formula I as claimed in claim 1, in which three radicalsX are each ##STR14## and one radical X is a radical of the formula IV.4. A composition useful as a paraffin dispersant in mineral oil middledistillates, comprising an effective paraffin dispersant amount of acompound I or II as claimed in claim 1, in a hydrocarbon mixture havingan initial boiling point above 160° C. and a final boiling point ofbelow 420° C.